1. Field of the Invention
The present invention relates to an imager comprising an imaging sensor that captures an image using a rolling shutter.
2. Description of the Related Art
A well known imaging sensor used for capturing images has photodiodes arranged on a two-dimensional plane.
For example, a CMOS imaging sensor is one such imaging sensor. A conventional contrast AF procedure uses a contrast value from image data output by the CMOS imaging sensor to determine whether a photographing lens is focused on a subject. Focusing conditions are determined from contrast values in an AF region that is virtually provided on the CMOS imaging sensor.
However, in the case that focusing conditions change while the CMOS imaging sensor is outputting image data, the output image data becomes distorted so that it may not be determined properly whether a photographing lens is focused on a subject.